First I would try to used a pair of vice grip plyiers to grab the cable under the dash and pull it as hard as you can. Wiggle it in and out trying to free it up.

The cable gets rusted and binds and that is what happens since the handle is plastic.

While you are pulling on the cable have someone else wiggle the hood up and down trying to free the latch.

If this doesn't work the only other way to open it is to jack the car up a little and slide under it. You will have to remove the under panel and use a light to see the bottom of the latches. There are two. One on each side of the hood. You will have to use a long skinny screw driver and try to release the latch manually on each side. Sorry those are the only ways.

NOTE: If you just need to get the car started the only other option is to get a alegator clip with a thick wire and crimp it to the possitive bolt on the back of the alternator. Then use the jumper pack or jumper cable and attatch it to this wire being careful not to let it touch ground. (It will spark if you touch the body with it.

Then attach the other cable to the frame somer where there is bare metal to act as the ground. THen start it up. You can then drive it to a shop to pop the hood for you.